Effect of 0.3 at. % Ce on the corrosion resistance of Fe40Ni20Co20Cr20 high-entropy alloy in 3.5 wt% NaCl solution.

• Trace amounts of Ce significantly refine the alloy grain size; • The addition of trace amounts of Ce improves the corrosion resistance of the alloy; • The strong surface activity of Ce inhibits the adsorption of Cl− on the metal surface； The impact of trace Ce doping on the pitting behavior of Fe 40 Ni 20 Co 20 Cr 20 high-entropy alloy in a 3.5 wt% NaCl solution was examined. The results indicate that the addition of trace Ce elements leads to a notable reduction in grain size and improved corrosion resistance of the alloy, the critical pitting potential of the alloy increased to 428 mv, and the corrosion resistance of the passivation film was significantly enhanced. This improvement can be mainly attributed to the strong surface activity of Ce, which promotes the formation of Cr 2 O 3 in the passivation film, resulting in a more stable and protective film layer. The ΔE (difference between corrosion potential and zero charge potential) of the high-entropy alloys (HEAs) was negative, indicating a decrease in the adsorption capacity of the electrochemical interface for Cl−. This reduction helps to mitigate pitting corrosion on the surface of the passivation film caused by Cl− erosion. [ABSTRACT FROM AUTHOR]